A first-of-its-kind study in Neuropsychology has found that decreased connectivity between network-specific brain regions is linked to the central deficit common to the various cognitive changes associated with multiple sclerosis (MS), slowed cognitive speed.

Researchers at The University of Texas at Dallas and The University of Texas Southwestern Medical Center recruited 29 participants with relapse-remitting MS and 23 age- and sex-matched healthy control to undergo functional magnetic resonance imaging (fMRI) while completing a measure of cognitive processing speed. Study participants were given four seconds to view a nine-item key of number and symbol pairs (for example '+' above the number 3) and one number-symbol pair probe; they were then asked to indicate with a left or right thumb button press whether or not the probe appeared in the key.

Accuracy was similar for both groups but response times for individuals with MS were much slower. A review of the fMRI data showed that MS patients had weaker functional connections with dorsolateral prefrontal cortex while completing the task. The authors posit that the diminished connections are likely due to decreased white matter surrounding the neurons in the brain.

These results emphasize need for treatments targeting white matter structures and white matter proliferation, the authors concluded. They are presenting conducting research to further explore the physiology of white matter to better understand cognitive speed reductions in patients with MS, as well as in healthy aging individuals.